Offspring sex ratio variation in relation to brood size and mortality in a promiscuous species: the Aquatic Warbler <i>Acrocephalus paludicola</i>

Dyrcz, Andrzej; Sauer‐Gürth, Hedwig; Tkadlec, Emil; Wink, Michael

doi:10.1046/j.1474-919x.2004.00256.x

Cited by 22 publications

(18 citation statements)

References 56 publications

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“…Such male biased hatching failure has been recently shown in a study of a natural population of tree swallows Tachycineta bicolor (Whittingham and Dunn 2001), and in captive zebra finches Taenopygia guttata (Rutkowska and Cichoń 2002). The diverging sex ratio between complete and partial broods was also reported in aquatic warbler Acrocephalus paludicola (Dyrcz et al 2004), but sex biased embryo mortality was not found in studies of sparrowhawk Accipiter nisus (van den Burg et al 2002). There is also some evidence that prenatal mortality is male‐biased in a variety of mammal species (Clutton‐Brock 1991, for review).…”

Section: Discussionmentioning

confidence: 66%

Male‐biased sex ratio among unhatched eggs in great tit Parus major, blue tit P. caeruleus and collared flycatcher Ficedula albicollis

Cichoń¹,

Sendecka²,

Gustafsson³

2005

Journal of Avian Biology

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Male-biased sex ratio among unhatched eggs in great tit Parus major, blue tit P. caeruleus and collared flycatcher Ficedula albicollis Mariusz Cichoń, Joanna Sendecka and Lars Gustafsson Cichoń , M., Sendecka, J. and Gustafsson, L. 2005. Male-biased sex ratio among unhatched eggs in great tit Parus major, blue tit P. caeruleus and collared flycatcher Ficedula albicollis. Á/ J. Avian Biol. 36: 386 Á/390.An increasing number of studies have demonstrated that brood sex ratios are frequently unequal, but the proximate mechanisms underlying this deviation are largely unknown. In the current study we analysed deviation from expected 1:1 sex ratio among dead embryos from unhatched eggs collected from partially unhatched clutches of three passerine bird species. We showed that male embryos were significantly overrepresented among unhatched eggs of great tit Parus major, blue tit P. caeruleus and collared flycatcher Ficedula albicollis. Moreover, the bias in sex ratio differed among species and tended to differ among study years. We discuss several hypotheses to explain the observed male bias among unhatched eggs. We conclude that sex specific embryo mortality may contribute to explain the observed variation in sex ratios in several species of wild birds and that sexing unhatched eggs is important in studies of sex ratio allocation. M. Cichoń

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Section: Discussionmentioning

confidence: 66%

Male‐biased sex ratio among unhatched eggs in great tit Parus major, blue tit P. caeruleus and collared flycatcher Ficedula albicollis

Cichoń¹,

Sendecka²,

Gustafsson³

2005

Journal of Avian Biology

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“…2006). All these factors are interrelated, and it is not yet clear whether skewed offspring sex ratios are adaptive, or what their proximate or ultimate drivers are (Weatherhead & Teather 1991, Sheldon 1998, Dyrcz et al . 2004, Ewen et al .…”

Section: Results and Reviewmentioning

confidence: 99%

“…1996, Griffith et al . 2003, clutch size (Dyrcz et al . 2004), age at first breeding , postnatal dispersal patterns (Gowaty 1993, Julliard 2000, the presence or contribution of nest helpers or brood parasites (Komdeur 1998, Legge et al .…”

Section: Offspring Sex Ratiosmentioning

confidence: 99%

Adult sex ratios in wild bird populations

Donald¹

2007

Ibis

418

540

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Offspring sex ratios in wild bird populations, and the extent to which they vary from the equality expected by random genotypic sex determination, have received much recent attention. Adult sex ratios (ASRs) in wild birds, on the other hand, remain very poorly described, and many of the questions about them posed by Ernst Mayr in 1939 remain unanswered. This review assesses population-level sex ratio patterns in wild bird populations, with an emphasis on the ASR. A quantitative assessment of over 200 published estimates of ASR, covering species from a wide range of taxa, regions and habitats, supported Mayr's assertion that skewed ASRs are common in wild bird populations. On average, males outnumbered females by around 33%, and 65% of published estimates differed significantly from equality. In contrast, populationlevel estimates of offspring sex ratio in birds did not generally differ from equality, and mean ASR across a range of wild mammal species was strongly female-skewed. ASR distortion in birds was significantly more severe in populations of globally threatened species than in nonthreatened species, a previously undescribed pattern that has profound implications for their monitoring and conservation. Higher female mortality, rather than skewed offspring sex ratio, is the main driver of male-skewed ASRs in birds, and the causes and implications of this are reviewed. While estimates of ASR in wild bird populations may be subject to a number of biases, which are discussed, there is currently no quantitative evidence that an ASR of one male to one female represents the norm in birds. A better understanding and reporting of ASRs in wild bird populations could contribute greatly to our understanding of population processes and could contribute much to theoretical and applied research and conservation.

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“…In birds, brood sex ratio can be biased in response to environmental conditions (Oddie 2000; Suorsa et al . 2003; Dyrcz et al . 2004; Szekely et al .…”

Section: Discussionmentioning

confidence: 99%

Behavioural flexibility in the mating system buffers population extinction: lessons from the lesser spotted woodpecker Picoides minor

Rossmanith

Grimm

Blaum

et al. 2006

Journal of Animal Ecology

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Summary 1.In most stochastic models addressing the persistence of small populations, environmental noise is included by imposing a synchronized effect of the environment on all individuals. However, buffer mechanisms are likely to exist that may counteract this synchronization to some degree. 2. We have studied whether the flexibility in the mating system, which has been observed in some bird species, is a potential mechanism counteracting the synchronization of environmental fluctuations. Our study organism is the lesser spotted woodpecker Picoides minor (Linnaeus), a generally monogamous species. However, facultative polyandry, where one female mates with two males with separate nests, was observed in years with male-biased sex ratio. 3. We constructed an individual-based model from data and observations of a population in Taunus, Germany. We tested the impact of three behavioural scenarios on population persistence: (1) strict monogamy; (2) polyandry without costs; and (3) polyandry assuming costs in terms of lower survival and reproductive success for secondary males. We assumed that polyandry occurs only in years with male-biased sex ratio and only for females with favourable breeding conditions. 4. Even low rates of polyandry had a strong positive effect on population persistence. The increase of persistence with carrying capacity was slower in the monogamous scenario, indicating strong environmental noise. In the polyandrous scenarios, the increase of persistence was stronger, indicating a buffer mechanism. In the polyandrous scenarios, populations had a higher mean population size, a lower variation in number of individuals, and recovered faster after a population breakdown. Presuming a realistic polyandry rate and costs for polyandry, there was still a strong effect of polyandry on persistence. 5. The results show that polyandry and in general flexibility in mating systems is a buffer mechanism that can significantly reduce the impact of environmental and demographic noise in small populations. Consequently, we suggest that even behaviour that seems to be exceptional should be considered explicitly when predicting the persistence of populations.

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Offspring sex ratio variation in relation to brood size and mortality in a promiscuous species: the Aquatic Warbler Acrocephalus paludicola

Cited by 22 publications

References 56 publications

Male‐biased sex ratio among unhatched eggs in great tit Parus major, blue tit P. caeruleus and collared flycatcher Ficedula albicollis

Male‐biased sex ratio among unhatched eggs in great tit Parus major, blue tit P. caeruleus and collared flycatcher Ficedula albicollis

Adult sex ratios in wild bird populations

Behavioural flexibility in the mating system buffers population extinction: lessons from the lesser spotted woodpecker Picoides minor

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